From Handbook of Machining and Metalworking Calculations
9.1 PULLOUT CALCULATIONS AND BOLT CLAMP LOADS
Screw thread systems are shown with their basic geometries and dimensions in Sec. 5.2.
Engagement of Threads. The length of engagement of a stud end or bolt end E can be stated in terms of the major diameter D of the thread. In general,
For a steel stud in cast iron or steel, E = 1.50 D.
For a steel stud in hardened steel or high-strength bronze, E = D.
For a steel stud in aluminum or magnesium alloys subjected to shock loads, E = 2.00 D + 0.062.
For a steel stud as described, subjected to normal loads, E = 1.50 D + 0.062.
Load to Break a Threaded Section. For screws or bolts,
where P b = load to break the screw or bolt, lbf
S = ultimate tensile strength of screw or bolt material, lb/in 2
A ts = tensile stress area of screw or bolt thread, in 2
NOTE. UNJ round-root threads will develop higher loads and have higher endurance limits.
Tensile Stress Area Calculation. The tensile stress area A ts of screws and bolts is derived from
where A ts = tensile stress area, in 2
D = basic major diameter of thread, in
n = number of threads per inch
NOTE. You may select the stress areas...
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A screw is a wide-encompassing type of hardware fastener that attributes its mechanical capabilities to the helical groove that extends around the circumference of the device's shank. These threads provide the friction and traction that serves a screw's purpose: to assemble or position two workpieces in relation to each other. While used synonymously, screws and bolts are not mechanical clones.
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